Machines such as, for example, dozers, motor graders, wheel loaders, wheel tractor scrapers, and other types of heavy equipment are used to perform a variety of tasks. Effective control of the machines requires accurate and responsive sensor reading to perform calculations providing information in near real time to the machine control or operator. Autonomously and semi-autonomously controlled machines are capable of operating with little or no human input by relying on information received from various machine systems. For example, based on machine movement input, terrain input, and/or machine operational input, a machine can be controlled to remotely and/or automatically complete a programmed task. By receiving appropriate feedback from each of the different machine systems and sensors during performance of the task, continuous adjustments to machine operation can be made that help to ensure precision and safety in completion of the task. In order to do so, however, the information provided by the different machine systems and sensors should be accurate and reliable. The position, velocity, and distance traveled by the machine, and positions, movements, and orientations of different parts or components of the machine are parameters whose accuracy may be important for control of the machine and its operations.
Conventional machines typically utilize a navigation or positioning system to determine various operating parameters such as position, velocity, pitch rate, yaw rate, and roll rate for the machine. The position and orientation of the machine is referred to as the “pose” of the machine. The machine “state” includes the pose of the machine as well as various additional operating parameters that can be used to model the kinematics and dynamics of the machine, such as parameters characterizing the various links, joints, tools, hydraulics, and power systems of the machine. Some conventional machines utilize a combination of one or more of Global Navigation Satellite System (GNSS) data, a Distance Measurement Indicator (DMI) or odometer measurement data, Inertial Measurement Unit (IMU) data, etc. to determine these parameters. Some machines utilize RADAR sensors, SONAR sensors, LIDAR sensors, IR and non-IR cameras, and other similar sensors to help guide the machines safely and efficiently along different kinds of terrain. Conventional machines have attempted to fuse these different types of data to determine the position of a land-based vehicle.
An exemplary system that may be utilized to determine the position of a machine is disclosed in U.S. Patent Application Publication No. 2008/0033645 (“the '645 publication”) to Levinson et al. that published on Feb. 7, 2008. The system of the '645 publication utilizes location data from sensors such as Global Positioning System (GPS), as well as scene data from a LIDAR (light detection and ranging) device to determine a location or position of the machine. Specifically, the data is used to create a high-resolution map of the terrain and the position of the machine is localized with respect to the map.
Although the system of the '645 publication may be useful in determining the overall position of the machine, the system may not provide accurate estimates for the position of the machine or components of the machine while dead-reckoning (i.e., during periods of time when GPS signals are unavailable). Moreover, the system of the '645 publication may not provide accurate position information when GPS signals are unreliable or erroneous due to multipath errors, position jumps, etc. because the system of the '645 publication does not check for the accuracy of the GPS signal.
The system and method for using sensor fusion feedback for controlling fluid pressures in a machine according to the present disclosure is directed toward solving one or more of the problems set forth above and/or other problems of the prior art.